Day 25

This is terrible, but it's Christmas and I don't want to solve this intense graph theory problem right now. I fed the parsed graph into graphviz so I could see where the connections were, then had the code sever them and calculate the independent graph sizes.

Maybe I'll find a real solve for this later...but probably not.

advent-of-code-2023.csproj

@@ -77,6 +77,8 @@
 	  <EmbeddedResource Include="inputs\21a.txt" />
 	  <EmbeddedResource Include="inputs\24.txt" />
 	  <EmbeddedResource Include="inputs\24a.txt" />
+	  <EmbeddedResource Include="inputs\25.txt" />
+	  <EmbeddedResource Include="inputs\25a.txt" />
 	  <None Remove="inputs\22.txt" />
 	  <EmbeddedResource Include="inputs\22.txt" />
 	  <None Remove="inputs\22a.txt" />

inputs/25a.txt

@@ -0,0 +1,13 @@
+jqt: rhn xhk nvd
+rsh: frs pzl lsr
+xhk: hfx
+cmg: qnr nvd lhk bvb
+rhn: xhk bvb hfx
+bvb: xhk hfx
+pzl: lsr hfx nvd
+qnr: nvd
+ntq: jqt hfx bvb xhk
+nvd: lhk
+lsr: lhk
+rzs: qnr cmg lsr rsh
+frs: qnr lhk lsr

src/25.cs

@@ -0,0 +1,115 @@
+using aoc2023.Util;
+
+namespace aoc2023;
+
+internal class Day25 : Day
+{
+    private Dictionary<string, List<string>> connections = [];
+    internal override void Parse()
+    {
+        var lines = Util.Parsing.ReadAllLines($"{GetDay()}");
+        foreach (var line in lines)
+        {
+            var split = line.Split(": ");
+            var right = split[1].Split(' ', StringSplitOptions.RemoveEmptyEntries);
+            connections.TryAdd(split[0], []);
+            foreach (var r in right)
+            {
+                connections[split[0]].AddUnique(r);
+
+                connections.TryAdd(r, []);
+                connections[r].AddUnique(split[0]);
+            }
+        }
+
+        // Logger.LogLine("graph G {");
+        // foreach (var c in connections)
+        // {
+        //     Logger.LogLine($"{c.Key} -- {{ {string.Join(' ', c.Value)} }}");
+        // }
+        // Logger.LogLine("}");
+    }
+
+    internal override string Part1()
+    {
+        var br = connections.ToDictionary();
+        foreach (var b in br)
+        {
+            br[b.Key] = [..b.Value];
+            if (b.Key == "nqq")
+            {
+                br[b.Key].Remove("pxp");
+            }
+
+            if (b.Key == "pxp")
+            {
+                br[b.Key].Remove("nqq");
+            }
+
+            if (b.Key == "jxb")
+            {
+                br[b.Key].Remove("ksq");
+            }
+
+            if (b.Key == "ksq")
+            {
+                br[b.Key].Remove("jxb");
+            }
+
+            if (b.Key == "kns")
+            {
+                br[b.Key].Remove("dct");
+            }
+
+            if (b.Key == "dct")
+            {
+                br[b.Key].Remove("kns");
+            }
+        }
+
+        List<string> h1 = ["pxp", "dct", "ksq"];
+        List<string> h2 = ["nqq", "jxb", "kns"];
+        bool bfound = false;
+        while (!bfound)
+        {
+            bfound = true;
+            int c = h1.Count;
+            for (int i = 0; i < c; i++)
+            {
+                foreach (var n in br[h1[i]])
+                {
+                    if (!h1.Contains(n))
+                    {
+                        bfound = false;
+                        h1.Add(n);
+                    }
+                }
+            }
+        }
+
+        bfound = false;
+        while (!bfound)
+        {
+            bfound = true;
+            var c = h2.Count;
+            for (int i = 0; i < c; i++)
+            {
+                foreach (var n in br[h2[i]])
+                {
+                    if (!h2.Contains(n))
+                    {
+                        bfound = false;
+                        h2.Add(n);
+                    }
+                }
+            }
+        }
+
+        return $"{h1.Count} * {h2.Count} = <+white>{h1.Count * h2.Count}";
+    }
+
+    internal override string Part2()
+    {
+        return $"<red>M<green>e<red>r<green>r<red>y <green>C<red>h<green>r<red>i<green>s<red>t<green>m<red>a<green>s<red>!";
+    }
+}